Thermal insulation performance measurement apparatus and measurement method using the same

ABSTRACT

A thermal insulation performance measurement apparatus which measures thermal insulation performance of a thermal insulator by heat flux to the thermal insulator, measured by a heat flux sensor, and a measurement method using the same includes a heat flux sensor provided with one surface adapted to contact an object to be measured, a first heat source arranged on the upper surface of the heat flux sensor to supply heat to the heat flux sensor, a thermal insulator arranged on the upper surface of the first heat source, a third heat source arranged on the upper surface of the thermal insulator, and a second heat source arranged around the heat flux sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/747,625 filed Jan. 23, 2013 in the United States Patent and TrademarkOffice, and claims the priority benefit of Korean Patent Application No.10-2012-0010458, filed on Feb. 1, 2012 and Korean Patent Application No.10-2012-0059278, filed on Jun. 1, 2012, in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein byreference.

BACKGROUND

1. Field

The following description relates to a measurement apparatus formeasuring thermal insulation performance of a thermal insulator throughvariation of heat flux measured by a heat flux sensor, and a measurementmethod using the same.

2. Description of the Related Art

In general, a vacuum insulation panel has excellent thermal insulationperformance when compared with existing thermal insulators, and is thusapplied to various fields, such as buildings, home appliances, etc. Sucha vacuum insulation panel includes a porous inner core membermaintaining the shape of the thermal insulator, an outer surface filmhaving gas barrier properties and surrounding the inner core member tomaintain a vacuum, and a gas desiccant to maintain the vacuum for a longtime. The thermal insulation performance of the vacuum insulation panelis determined according to the degree of vacuum of the inside of thevacuum insulation panel, and when pressure of the inside of the vacuuminsulation panel reaches a designated level or more, the thermalinsulation performance of the vacuum insulation panel is rapidlylowered. A getter or the desiccant within the vacuum insulation panelsuppresses such degradation of the thermal insulation performance causedby increase of the inner pressure of the vacuum insulation panel, andthus the vacuum insulation panel maintains high thermal insulationperformance for a long time. There are various factors causing thedegradation of the thermal insulation performance of the vacuuminsulation panel, and among these factors, the main factor ispenetration of gas due to damage to the outer surface film by externalimpact when the vacuum insulation panel is handled and transported. Theouter surface film includes a metal thin film formed of aluminum foilhaving a thickness of 6-7 μm to prevent gas penetration, an externalplastic film to protect the metal thin film, and a low densitypolyethylene (LDPE) layer serving as a heat fusion layer formanufacturing a pouch. When the outer surface film is torn, gas isinstantaneously introduced into the vacuum insulation panel, the vacuuminsulation panel is expanded, and thus gas penetration into the vacuuminsulation panel is recognized with the naked eye, but if a slow leakoccurs, gas penetration is slowly carried out and thus it may bedifficult to recognize such gas penetration with the naked eye due toinfluence of adsorption of the getter or the desiccant.

However, after the vacuum insulation panel has been embedded in arefrigerator or the wall of a building, it may be difficult to replacethe vacuum insulation panel with a new one. Particularly, in case of arefrigerator, when a defect of the vacuum insulation panel is detectedafter the vacuum insulation panel has been embedded in the refrigerator,the entirety of the refrigerator product is discarded. Therefore,necessity of executing a reliability test to check the inner pressure orthermal conductivity of the vacuum insulation panel before mounting ofthe vacuum insulation panel rises.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide athermal insulation performance measurement apparatus which rapidly andaccurately tests thermal insulation performance of a thermal insulator,and a measurement method using the same.

It is an aspect of the present disclosure to provide a thermalinsulation performance measurement apparatus which measures thermalinsulation performance of a thermal insulator when the thermal insulatoris installed within a product, and a measurement method using the same.

Additional aspects of the invention will be set forth in part in thedescription which follows and, in part, will be obvious from thedescription, or may be learned by practice of the invention.

In accordance with an aspect of the present disclosure, a thermalinsulation performance measurement apparatus includes a heat flux sensorprovided with one surface adapted to contact an object to be measured, afirst heat source arranged on the upper surface of the heat flux sensorto supply heat to the heat flux sensor, a second heat source arrangedaround the heat flux sensor to prevent generation of heat flow aroundthe heat flux sensor, and a thermal insulator arranged on the uppersurface of the first heat source.

The thermal insulation performance measurement apparatus may furtherinclude a third heat source arranged on the upper surface of the thermalinsulator to prevent generation of heat flow above the heat flux sensor.

The thermal insulation performance measurement apparatus may furtherinclude a controller to adjust temperatures of the first heat source,the second heat source, and the third heat source.

The controller may control the temperatures of the first heat source,the second heat source, and the third heat source so that thetemperatures of the first heat source, the second heat source, and thethird heat source are equal.

The heat flux sensor may be a contact-type heat flux sensor.

The thermal insulator may be a vacuum insulation panel or a vacuum glasspanel.

In accordance with an aspect of the present disclosure, an automaticmeasurement system includes a thermal insulation performance measurementapparatus including a heat flux sensor provided with one surface adaptedto contact an object to be measured, a first heat source arranged on theupper surface of the heat flux sensor to supply heat to the heat fluxsensor, a second heat source arranged around the heat flux sensor toprevent generation of heat flow around the heat flux sensor, and athermal insulator arranged on the upper surface of the first heatsource, a drive device moving the thermal insulation performancemeasurement apparatus forwards and backwards and bringing the thermalinsulation performance measurement apparatus into contact with theobject to be measured at a designated pressure, and a rod cell tomeasure pressure applied between the thermal insulation performancemeasurement apparatus and the object to be measured.

The drive device may include a motor to provide driving force, and aball screw to convert a rotational motion generated from the motor intoa linear motion.

The drive device may include an air cylinder.

In accordance with an aspect of the present disclosure, a thermalinsulation performance measurement method includes heating a heat fluxsensor to a designated temperature, heating a region around the heatflux sensor to the designated temperature to prevent generation of heatflow at the region around the heat flux sensor, heating a region abovethe heat flux sensor to the designated temperature to prevent generationof heat flow at the region above the heat flux sensor, and measuringthermal insulation performance of an object to be measured by first heatflux measured by the heat flux sensor through contact of the heat fluxsensor heated to the designated temperature with the object to bemeasured.

The thermal insulation performance of the object to be measured may bemeasured by the first heat flux measured by the heat flux sensor after adesignated time from contact of the heat flux sensor with the object tobe measured has elapsed.

The measurement of the thermal insulation performance of the object tobe measured may include measuring first thermal conductivities of pluralsamples using a thermal conductivity measurement apparatus, acquiringfirst data regarding the relationship between the first thermalconductivities and second heat fluxes by measuring the second heatfluxes of the samples using the heat flux sensor, and measuring thethermal insulation performance of the object to be measured byestimating thermal conductivity of the object to be measured using thesecond heat flux based on the first data.

The measurement of the thermal insulation performance of the object tobe measured may include measuring first thermal conductivities of avacuum insulation panel, the inner pressure of which is adjustable,using a thermal conductivity measurement apparatus while adjusting theinner pressure of the vacuum insulation panel, acquiring first dataregarding a relationship between the first thermal conductivities andsecond heat fluxes by measuring the second heat fluxes of the vacuuminsulation panel using the heat flux sensor, and measuring the thermalinsulation performance of the vacuum insulation panel by estimatingthermal conductivity of the vacuum insulation panel using the secondheat flux based on the first data.

The measurement of the thermal insulation performance of the object tobe measured may further include measuring third heat fluxes of thevacuum insulation panel, the inner pressure of which is adjustable, atrespective degrees of the inner pressure of the vacuum insulation panelusing the heat flux sensor while adjusting the inner pressure of thevacuum insulation panel to the respective degrees, and correcting thefirst data by comparing the third heat fluxes with third data regardinga relationship between the degree of the vacuum of the inside and thethermal conductivity of the vacuum insulation panel.

In accordance with an aspect of the present disclosure, a refrigeratorincludes an outer case forming the external appearance of therefrigerator, an inner case disposed at the inside of the outer case andforming storage chambers, and thermal insulation members embeddedbetween the outer case and the inner case to block cold air in thestorage chambers, wherein the thermal insulation members include firstthermal insulation members formed of a vacuum insulation panel attachedto the inner surface of the outer case, and second thermal insulationmembers formed by injecting urethane foam into a space between the outercase and the inner case, remaining after the first thermal insulationmembers are been arranged, and before the first thermal insulationmembers formed of the vacuum insulation panel are attached to the outercase, only first thermal insulation members formed of the vacuuminsulation panel, designated thermal insulation performance of which hasbeen secured using a thermal insulation performance measurementapparatus, are used to form the thermal insulation members, and thusdisposal of a product due to a defect of the final thermal insulationmembers is prevented.

The thermal insulation performance measurement apparatus may include aheat flux sensor, a first heat source arranged on the upper surface ofthe heat flux sensor to supply heat to the heat flux sensor, and asecond heat source arranged around the heat flux sensor to preventmovement of heat flow to a region around the heat flux sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the invention will become apparent andmore readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a perspective view of a thermal insulation performancemeasurement apparatus in accordance with an embodiment of the presentdisclosure;

FIG. 2 is a view illustrating the lower portion of the thermalinsulation performance measurement apparatus;

FIG. 3 is a cross-sectional view illustrating the inner structure of thethermal insulation performance measurement apparatus;

FIG. 4 is an exploded perspective view illustrating the inner structureof the thermal insulation performance measurement apparatus;

FIG. 5 is a graph illustrating variation in heat flux measured throughthe thermal insulation performance measurement apparatus;

FIG. 6 is a graph illustrating a relationship between thermalconductivity and heat flux;

FIG. 7 is a view illustrating a vacuum insulation panel, the innerpressure of which is adjustable;

FIG. 8 is a graph illustrating a relationship between the inner pressureand thermal conductivity of a vacuum insulation panel;

FIG. 9 is a view illustrating an automatic measurement system inaccordance with an embodiment of the present disclosure;

FIG. 10 is a view illustrating a state in which the thermal insulationperformance measurement apparatus is used to measure thermal insulationperformance of a vacuum glass panel;

FIG. 11 is a view illustrating a state in which thermal insulationperformance of a thermal insulator embedded in a refrigerator is testedusing the thermal insulation performance measurement apparatus; and

FIG. 12 is view illustrating an automatic measurement system forrefrigerators in accordance with an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout. The embodiments are described below to explain the presentdisclosure by referring to the figures.

Hereinafter, a thermal insulation performance measurement apparatus inaccordance with an embodiment of the present disclosure will bedescribed with reference to the accompanying drawings.

As shown in FIGS. 1 to 4, a thermal insulation performance measurementapparatus 10 includes a cover 11 forming the external appearance of thethermal insulation performance measurement apparatus 10, and a handle 12installed on the upper portion of the cover 11.

The cover 11 is configured such that the lower portion of the cover 11opposite the upper surface of the cover 11 on which the handle 12 isinstalled is opened, and the thermal insulation performance measurementapparatus 10 may include a heat flux sensor 100, a first heat source120, a second heat source 110, a thermal insulator 130, and a third heatsource 140, which are installed within the cover 11.

The heat flux sensor 100 may be arranged at the center of the openedlower portion of the cover 11 to contact the surface of an object V tobe measured. The heat flux sensor 100 may be a contact-type heat fluxsensor 100, and in this case, the heat flux sensor 100 may include afilm-type thin sheet.

In the heat flux sensor 100, a heat flux measurement direction is set.The heat flux sensor 100 may be arranged such that the heat fluxmeasurement direction is toward the object V to be measured.

The first heat source 120 to heat the heat flux sensor 100 to adesignated temperature is arranged on the upper surface of the heat fluxsensor 100. The first heat source 120 may be configured in a shape inwhich an electric heater is inserted into a metal having excellentthermal conductivity, such as copper or aluminum, for example, or in atype in which a thin film heater is attached to a metal. Further, thefirst heat source 120 may be configured such that a fluid heated to aconstant temperature is circulated, and may include a temperature sensor121 to sense the temperature of the heat flux sensor 100 and the firstheat source 120. The first heat source 120 may be provided with onesurface having a size corresponding to the upper surface of the heatflux sensor 100 to cover the entirety of the upper surface of the heatflux sensor 100.

The second heat source 110 is arranged around the heat flux sensor 100and the first heat source 120, and may have the same thickness as thesum of the thickness of the heat flux sensor 100 and the thickness ofthe first heat source 120. The second heat source 110 may be configuredin a shape in which an electric heater is inserted into a metal or in atype in which a thin film heater is attached to a metal, in the samemanner as the first heat source 120. Further, the second heat source 110may be configured such that a fluid heated to a constant temperature iscirculated, and may include temperature sensors 111 to sense thetemperature of the second heat source 110.

A support member 150 to support the second heat source 110 to maintainthe separation state between the second heat source 110 and the innersurface of the cover 11 may be installed between the second heat source110 and the inner surface of the cover 11.

The support member 150 supports the second heat source 110 in theseparation state from the inner surface of the cover 11, thus minimizingheat transfer to the cover 11 when the second heat source 110 isoperated. Therefore, the support member 150 prevents the cover 11 frombeing heated close to the temperature of the second heat source 110.

A thermal insulator 130 having excellent thermal insulation performanceto direct all of heat generated from the first heat source 120 to theobject V to be measured may be arranged on the upper surfaces of thefirst heat source 120 and the second heat source 110. Such a thermalinsulator 130 may be formed of a vacuum insulation panel (VIP).

The third heat source 140 may be provided on the upper surface of thethermal insulator 130. The third heat source 140 may be configured in ashape in which an electric heater is inserted into a metal or in a typein which a thin film heater is attached to a metal, in the same manneras the first heat source 120 and the second heat source 110. Further,the third heat source 140 may be configured such that a fluid heated toa constant temperature is circulated, and may include a temperaturesensor 141 to sense the temperature of the third heat source 140.

The protective heat source 110, i.e., the second heat source 110, thefirst heat source 120, and the third heat source 140 may be heated bypower supplied from a controller 20 through an electric wire 13, and thetemperatures of the respective heat sources 110, 120, and 140 measuredthrough the temperature sensors 111, 121, and 141 installed on therespective heat sources 110, 120, and 140 are input to the controller 20through the electric wire 130.

The controller 20 controls power supply to the first heat source 120 andthe rear heat source 140, i.e., the third heat source 140, whilemonitoring the temperatures of the first heat source 120 and the thirdheat source 140 measured through the temperature sensors 121 and 141installed on the first heat source 120 and the third heat source 140,thereby controlling the first heat source 120 and the third heat source140 to reach the same temperature. When the first heat source 120 andthe third heat source 140 are set to the same temperature, a temperaturedifference between the first heat source 120 and the third heat source140 becomes 0 and thus flow of heat is not generated, andsimultaneously, heat flux in the direction opposite to the object V tobe measured based on the first heat source 120 becomes 0 by the thermalinsulator 130 located between the first heat source 120 and the thirdheat source 140 and thus accuracy in measurement is increased.

In the same manner, the controller 20 controls power supply to the firstheat source 120 and the second heat source 110 according to thetemperatures of the first heat source 120 and the second heat source 110measured through the temperature sensors 121 and 111 installed on thefirst heat source 120 and the second heat source 120, therebycontrolling the first heat source 120 and the second heat source 110 toreach the same temperature. Consequently, the controller 20 may controloperation of the first heat source 120, the third heat source 140, andthe second heat source 110 such that the temperatures of the rear heatsource 140 and the second heat source 110 are the same as thetemperature of the first heat source 120.

If the first heat source 120 and the second heat source 110 are set tothe same temperature, as described above, there is not a temperaturedifference between the second heat source 110 and the heat flux sensor100 heated to the same temperature as the first heat source 120 by thefirst heat source 120, and thus heat flux between the heat flux sensor100 and the second heat source 110 on the surface of the object V to bemeasured may substantially become 0 when the thermal insulationperformance measurement apparatus 10 contacts the object V to bemeasured. Further, the above three heat sources 110, 120, and 140 maymaintain the same temperature at any time through proportional integralderivative (PID) temperature control, and thus continuous measurementmay be executed.

The second heat source 110 may be arranged around the first heat source120, and be separated from the heat flux sensor 100 and the first heatsource 120 by a designated interval.

The thermal insulator 130 arranged between the first heat source 120 andthe third heat source 140 blocks heat flow due to low heat transfercoefficient thereof even if a fine temperature difference between thefirst heat source 120 and the third heat source 140 is instantaneouslygenerated, and may thus serve as a buffer to prevent generation of heatflux between the first heat source 120 and the third heat source 140.

Therefore, because heat fluxes in all directions except for a directiontoward the object V to be measured based on the heat flux sensor 100 maysubstantially become 0, all heat fluxes measured by the heat flux sensor100 contacting the object V to be measured in a state in which thetemperatures of the heat flux sensor 100, the first heat source 120, thesecond heat source 110, and the third heat source 140 become equal maybe reliably regarded as heat fluxes generated between the heat fluxsensor 100 and the object V to be measured.

Hereinafter, a method of measuring thermal insulation performance of theobject V to be measured using the thermal insulation performancemeasurement apparatus 10 in accordance with an embodiment of the presentdisclosure will be described in detail.

First, in order to measure thermal insulation performance, the heat fluxsensor 100 is preheated to a designated temperature by the first heatsource 120, and the second heat source 110 and the third heat source 140are heated to the same temperature as the temperature of the heat fluxsensor 100 and the first heat source 120. Here, the heating temperaturemay be from approximately 70° C. to approximately 90° C.

When the temperatures of the heat flux sensor 100, the first heat source120, the second heat source 110, and the third heat source 140 becomeequal, measurement may be started.

In order to execute measurement, the heat flux sensor 100 and the secondheat source 110 arranged on the lower surface of the cover 11 arebrought into contact with the surface of the object V to be measured.Here, the object V to be measured may be a vacuum insulation panel. Thevacuum insulation panel, as shown in FIG. 3, may include a porous coremember V2, and a protective film V1 surrounding the outer surface of thecore member V2 and maintaining the vacuum state of the core member V2.

As shown in FIG. 5, before the heat flux sensor 100 contacts the objectV to be measured, i.e., the vacuum insulation panel, the heat flux valuemeasured by the heat flux sensor 100 is low, and when the heat fluxsensor 100 and the second heat source 110 are brought into contact withthe surface of the object V to be measured, i.e., the vacuum insulationpanel, the heat flux value measured by the heat flux sensor 100 israpidly raised. The reason for this is that the thermal conductivity ofthe protective film V1 of the vacuum insulation panel forming thesurface of the vacuum insulation panel is higher than the thermalconductivity of the inner core member V2, and thus high heat flux isgenerated toward the protective film V1 having a relatively high thermalconductivity in the early stage in which the heat sensor 100 contactsthe surface of the vacuum insulation panel, due to a kind of surfaceeffect.

However, as time goes by after contact of the heat flux sensor 100 withthe surface of the vacuum insulation panel V, the heat flux valuemeasured by the heat flux sensor 100 is gradually lowered. The reasonfor this is that the heat flux value is rapidly raised by metal foillaminated in the protective film V1 in the early state of contact, butas time goes by, the protective film V1 is heated to a temperaturesimilar to the temperature of the heat flux sensor 100, the surfaceeffect disappears, and low thermal conductivity characteristics of thecore member V2 are reflected.

Therefore, the heat flux value measured by the heat flux sensor 100after a designated measurement standby time from contact of the heatflux sensor 100 with the vacuum insulation panel V has elapsed may beconsidered as an index of measurement of thermal insulation performance.

It is understood that, if the vacuum insulation panel is in a normalstate, the heat flux values measured by the heat flux sensor 10 areformed in a pattern as the curve G and are converged on a relatively lowvalue, but if the vacuum insulation panel is in an abnormal state, theheat flux values measured by the heat flux sensor 100 are converged on avalue as in the curve N, which is higher than the value on the curve G.

In case of the vacuum insulation panel V, the above measurement standbytime may be varied according to the material or thickness of theprotective film V1, and thus determined in consideration of securing ofreliability of measured values through repeated experimentation andnecessity of rapidly measuring thermal insulation performance. In caseof a general vacuum insulation panel, the measurement standby time maybe from approximately 7 seconds to approximately 15 seconds.

The heat flux value is finally measured by the heat flux sensor 100through the above-described process, but the heat flux value does notdirectly mean thermal conductivity.

However, because thermal conductivity and heat flux of a certain objectare linearly proportional to each other, a graph illustrating arelationship between thermal conductivity and heat flux, as shown inFIG. 6, may be acquired by measuring heat fluxes of a plurality ofdifferent thermal insulators, thermal conductivities of which aremeasured in advance through a separate thermal conductivity measurementapparatus (not shown), through the thermal insulation performancemeasurement apparatus 10 in accordance with the embodiment of thepresent disclosure and then establishing a database in which arelationship between the measured thermal conductivities and the heatfluxes measured through the thermal insulation performance measurementapparatus 10 are stored.

That is, the heat flux measured through the thermal insulationperformance measurement apparatus 10 is output in the shape of apotential difference through the heat flux sensor 100. However, thermalconductivity of the vacuum insulation panel V may be estimated using thedata prepared in advance, as shown in FIG. 6, and consequently, whetheror not the vacuum insulation panel is normally operated may be checkedby judging whether or not the vacuum insulation panel V has thermalconductivity within a normal range through the heat flux measuredthrough the thermal insulation performance measurement apparatus 10.

Further, the data regarding a relationship between thermal conductivityand heat flux may be periodically corrected by periodically measuringheat fluxes of plural different thermal insulators, thermalconductivities of which are measured in advance through a separatethermal conductivity measurement apparatus (not shown), through thethermal insulation performance measurement apparatus 10 in accordancewith the embodiment of the present disclosure in the above-describedmethod.

Further, data regarding a relationship between thermal conductivity andheat flux may be acquired using a vacuum insulation panel A, the innerpressure of which is measurable and adjustable, as shown in FIG. 7, andthe data regarding these relationships may be periodically corrected.

In the vacuum insulation panel A, the inner pressure of which ismeasurable and adjustable, as shown in FIG. 7, includes a pressure gaugeA1 measuring the inner pressure of the vacuum insulation panel A, and anadjustment valve A2 to adjust the inner pressure of the vacuuminsulation panel A. Therefore, a user may adjust the inner pressure (adegree of vacuum of the inside) of the vacuum insulation panel A throughthe adjustment valve A2 while monitoring the inner pressure of thevacuum insulation panel A through the pressure gauge A1.

Data regarding a relationship between thermal conductivities the vacuuminsulation panel A measured through a separate fine thermal conductivitymeasurement apparatus (not shown) under the condition that the innerpressure (the degree of vacuum of the inside) of the vacuum insulationpanel A is adjusted, and heat fluxes of the vacuum insulation panel Ameasured by the heat flux sensor 100 (with reference to FIG. 3), andthermal conductivity of the object to be measured may be estimated fromthe measured heat flux of the object V to be measured based on the data.

Further, the inner pressure of the vacuum insulation panel and thethermal conductivity of the vacuum insulation panel are inverselyproportional to each other, as shown in the graph of FIG. 8. Therefore,if the inner pressure (the degree of vacuum of the inside) of the vacuuminsulation panel is given, the thermal conductivity of the vacuuminsulation panel may be estimated using the graph of FIG. 8. Throughsuch a method, the data regarding the relationship between thermalconductivity and heat flux may be corrected by calculating thermalconductivities of the vacuum insulation panel estimated according torespective inner pressures using the graph of FIG. 8 while adjusting theinner pressure of the vacuum insulation panel to several degrees, and bymeasuring the heat fluxes through the thermal insulation performancemeasurement apparatus 10 in accordance with the embodiment of thepresent disclosure.

The above graph of FIG. 8 is established through experimentation, and adetailed description thereof will thus be omitted.

The thermal insulation performance measurement apparatus 10 inaccordance with the embodiment of the present disclosure, as shown inFIG. 1, may constitute an automatic measurement system 200, as shown inFIG. 9. The automatic measurement system 200 may include a main frame210, a drive device 220 vertically moving the thermal insulationperformance measurement apparatus 10 to cause contact of the thermalinsulation performance measurement apparatus 10 with an object V to bemeasured at a constant pressure, a rod cell 230 to measure pressureapplied between the thermal insulation performance measurement apparatus10 and the object V to be measured, and guide rods 240 guiding verticalmovement of the drive device 220 and the rod cell 230 against the mainframe 210.

The drive device 220 may include a servomotor 221 to provide drivingforce, and a ball screw 222 to convert a rotational motion generatedfrom the servomotor 221 into a linear motion.

The rod cell 230 and the thermal insulation performance measurementapparatus 10 are installed under the drive device 220. Plural guide rods240 may be provided, and be combined with guide holes 212 provided onthe main frame 210 so that the drive device 220 may vertically moveagainst the main frame 210.

A nut part 223 of the ball screw 222 is installed on an upper plate 211of the main frame 210. Therefore, when a screw part 224 of the ballscrew 222 is rotated by the servomotor 221, the screw part 224vertically moves, and then the drive device 220, the thermal insulationperformance measurement apparatus 10 and the rod cell 230 verticallymove.

Now, an operating process of the automatic measurement system 200 willbe described. First, the object V to be measured is placed on a table213 on the main frame 210 below the thermal insulation performancemeasurement apparatus 10, and then the servomotor 221 is operated toinduce downward movement of the thermal insulation performancemeasurement apparatus 10. As the thermal insulation performancemeasurement apparatus 10 starts to contact the object V to be measured,the rod cell 230 senses pressure applied to the object V to be measuredby the thermal insulation performance measurement apparatus 10, theservomotor 221 is operated before such pressure reaches a proper value,operation of the servomotor 221 is stopped when the pressure reaches theproper value, and then a measuring process through the thermalinsulation performance measurement apparatus 10 is started.

Thereafter, when the measuring process through thermal insulationperformance measurement apparatus 10 has been completed, the servomotor221 is operated in the direction opposite to the rotation direction ofthe servomotor 221 when the thermal insulation performance measurementapparatus 10 moves downwards, and then the thermal insulationperformance measurement apparatus 10 moves upwards and is restored toits initial state.

Although the automatic measurement system 200 shown in FIG. 9illustrates the drive device 220 as including the servomotor 221 and theball screw 222, the drive device 220 is not limited thereto, and mayinclude any drive element causing a linear reciprocating motion. Forexample, the drive device 220 may include an air cylinder operated bypneumatic pressure, a hydraulic cylinder operated by hydraulic pressure,or a linear motor. Further, the servomotor 221 of the drive device 220may be replaced with a stepper motor.

As shown in FIG. 10, the thermal insulation performance measurementapparatus 10 in accordance with the embodiment of the present disclosureis not limited to the vacuum insulation panel as an object to bemeasured, and may be applied to a vacuum glass panel G. The automaticmeasurement system 200 or the thermal insulation performance measurementapparatus 10 manually operated may be used to measure thermal insulationperformance of the vacuum glass panel G in which a vacuum space G2 isformed between two glass sheets G1. However, differently from the outersurface film of the vacuum insulation panel, a considerable time istaken for heat to pass through the glass sheets, and thus a time takento measure thermal insulation performance of the vacuum glass panel Gafter stabilization of heat flux may be long, such as approximately 1minute, for example.

Further, a method of measuring thermal insulation performance of athermal insulator, such as a vacuum insulation panel, through thethermal insulation performance measurement apparatus 10 in accordancewith the embodiment of the present disclosure may be used as a method ofmeasuring thermal insulation performance of a thermal insulator embeddedin a refrigerator.

As shown in FIG. 11, in order to measure thermal insulation performanceof a thermal insulator embedded in a refrigerator R, the thermalinsulation performance measurement apparatus 10 approaches the outerwall of the refrigerator R so that the heat flux sensor 100 (withreference to FIG. 3) and the second heat source 110 (with reference toFIG. 3) contacts the outer wall of the refrigerator R, and then appliespressure to the outer wall of the refrigerator R.

Because the outer wall of the refrigerator R is formed of a metal panelor a plastic resin having higher thermal conductivity than a thermalinsulator installed within the refrigerator R, the heat flux value ofthe outer wall of the refrigerator R measured by the heat flux sensor100 is rapidly raised in the early state of measurement in the samemanner as the vacuum insulation panel. Particularly, because the outerwall of the refrigerator R has a greater thickness than the protectivefilm of the vacuum insulation panel, a time taken to heat the outer wallof the refrigerator R to a temperature similar to the temperature of theheat flux sensor 100 to remove the surface effect may be longer than thetime taken in the vacuum insulation panel. Therefore, the measurementstandby time of the thermal insulator embedded in the refrigerator R maybe longer than that of the vacuum insulation panel. However, when theouter wall of the refrigerator R is heated to a similar temperature tothe temperature of the heat flux sensor 100 and the surface effectdisappears, the thermal insulation effect of the thermal insulator isreflected in the heat flux value, and thus the measured heat flux valueis gradually decreased and converged into a designated value as timegoes by. Therefore, a time taken to converge the measured value isserved as the measurement standby time, and whether or not the thermalinsulator embedded in the refrigerator R is normally operated may bechecked using the measured value after the measurement standby time fromstarting of measurement has elapsed.

As shown in FIG. 12, the thermal insulation performance measurementapparatus 10 in accordance with the embodiment of the present disclosuremay constitute an automatic measurement system 300 for refrigerators tomeasure thermal insulation performance of a thermal insulator embeddedin a refrigerator R.

The automatic measurement system 300 for refrigerators may includethermal insulation performance measurement apparatuses 10 arranged atboth sides of the refrigerator R, drive devices 320 horizontally movingthe thermal insulation performance measurement apparatuses 10, and aframe 310 to support the drive devices 320 and the thermal insulationperformance measurement apparatuses 10, and the overall configuration ofthe automatic measurement system 300 for refrigerators except for theframe 310 may be similar to that of the above-described automaticmeasurement system 200 shown in FIG. 9.

The drive device 320 may include a servomotor 321 and a ball screw 322in the same manner as the drive device 220 of the above-describedautomatic measurement system 200 shown in FIG. 9.

In the same manner as the drive device 220 of the above-describedautomatic measurement system 200 shown in FIG. 9, the drive device 320may include an air cylinder operated by pneumatic pressure, a hydrauliccylinder operated by hydraulic pressure, or a linear motor, for example.

Further, a rod cell 330 to measure pressure applied to an object to bemeasured by the thermal insulation performance measurement apparatus 10when the thermal insulation performance measurement apparatus 10contacts the object to be measured may be installed between the drivedevice 320 and the thermal insulation performance measurement apparatus10.

The automatic measurement system 300 for refrigerators may be applied toa refrigerator manufacturing line and used as final quality testequipment to judge whether or not the thermal insulator embedded in theside surface of the refrigerator R moving along a conveyer belt (notshown) is normally operated by finally measuring thermal insulationperformance of the thermal insulator.

Particularly, even if the vacuum insulation panel V (with reference toFIG. 3) is judged as in a normal state in a test before the vacuuminsulation panel V is embedded in a refrigerator R, the protective filmV1 (with reference to FIG. 3) of the vacuum insulation panel V may bedamaged during embedment of the vacuum insulation panel V in therefrigerator R, the inner pressure of the vacuum insulation panel V maybe raised, and thus a defect of the vacuum insulation panel V may begenerated. Therefore, in order to prepare for the possibility of defectgeneration in the manufacture of the refrigerator R, whether or not thevacuum insulation panel is normally operated may be tested by measuringthermal insulation performance of the vacuum insulation panel within therefrigerator R using the automatic measurement system 300 in the finalstage of product manufacture.

The above-described embodiments may be recorded in computer-readablemedia including program instructions to implement various operationsembodied by a computer. The media may also include, alone or incombination with the program instructions, data files, data structures,and the like. The program instructions recorded on the media may bethose specially designed and constructed for the purposes ofembodiments, or they may be of the kind well-known and available tothose having skill in the computer software arts. Examples ofcomputer-readable media include magnetic media such as hard disks,floppy disks, and magnetic tape; optical media such as CD ROM disks andDVDs; magneto-optical media such as optical disks; and hardware devicesthat are specially configured to store and perform program instructions,such as read-only memory (ROM), random access memory (RAM), flashmemory, and the like. The computer-readable media may also be adistributed network, so that the program instructions are stored andexecuted in a distributed fashion. The program instructions may beexecuted by one or more processors. The computer-readable media may alsobe embodied in at least one application specific integrated circuit(ASIC) or Field Programmable Gate Array (FPGA), which executes(processes like a processor) program instructions. Examples of programinstructions include both machine code, such as produced by a compiler,and files containing higher level code that may be executed by thecomputer using an interpreter. The above-described devices may beconfigured to act as one or more software modules in order to performthe operations of the above-described embodiments, or vice versa.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. A thermal insulation performance measurementapparatus comprising: a heat flux sensor provided with a lower portioncontactable with a target measurement object; a first heat sourcedisposed in contact with an upper portion of the heat flux sensor tosupply heat to the heat flux sensor; a second heat source providedaround the first heat source so that a temperature thereof is maintainedat the same temperature as the first heat source and disposed separatelyfrom the first heat source by a predetermined distance; and an insulatordisposed on the first heat source.
 2. The apparatus of claim 1, whereinthe apparatus controls the first heat source and the second heat sourceto be maintained substantially at the same temperature.
 3. The apparatusof claim 1, wherein the insulator is disposed with a size correspondingto sizes of upper surfaces of the first heat source and the second heatsource.
 4. The apparatus of claim 1, wherein the second heat source isdisposed so that a height thereof is substantially the same as heightsfrom the target measurement object to the heat flux sensor and the firstheat source.
 5. The apparatus of claim 1, further comprising a thirdheat source disposed on the insulator to prevent generation of heat fluxabove the heat flux sensor.
 6. The apparatus of claim 5, furthercomprising a controller which controls temperatures of the first heatsource, the second heat source, and the third heat source.
 7. Theapparatus of claim 6, wherein the controller controls the temperaturesof the first heat source, the second heat source, and the third heatsource to be maintained substantially at the same temperature.
 8. Theapparatus of claim 1, wherein the heat flux sensor is in a contact typeand is a thin plate in a film form.
 9. The apparatus of claim 1, whereinthe insulator is a vacuum insulator.
 10. The apparatus of claim 5,wherein a temperature sensor is installed in each of the first, second,and third heat sources.
 11. The apparatus of claim 5, wherein atemperature of heating the first, second, and third heat sources is in arange of 70 to 90° C.
 12. An automatic measurement system comprising: athermal insulation performance measurement apparatus including: a heatflux sensor provided with a lower portion contactable with a targetmeasurement object; a first heat source disposed in contact with anupper portion of the heat flux sensor to supply heat to the heat fluxsensor; a second heat source provided around the first heat source sothat a temperature thereof is maintained at the same temperature as thefirst heat source and disposed separately from the first heat source bya predetermined distance; and an insulator disposed on the first heatsource; and a drive device configured to move the thermal insulationperformance measurement apparatus to contact the target measurementobject at a designated pressure.
 13. The system of claim 12, wherein thedrive device includes: a motor configured to supply power to the drivedevice; and a ball screw configured to convert a rotational motiongenerated from the motor into a linear motion.
 14. The system of claim12, wherein the drive device includes an air cylinder.
 15. A thermalinsulation performance measurement method of measuring thermalinsulation performance of an insulator embedded in a refrigerator byheat flux measured by the heat flux sensor after the heat flux sensor ofthe thermal insulation performance measurement apparatus of claim 1 isin contact with an outer wall of the refrigerator and a designated timehas elapsed.
 16. A thermal insulation performance measurement methodcomprising: heating a heat flux sensor up to a designated temperatureusing a first heat source; heating a second heat source disposed aroundthe heat flux sensor up to the designated temperature to preventgeneration of heat flux around the heat flux sensor; and measuringthermal insulation performance of a target measurement object by firstheat flux measured from the heat flux sensor by contacting the targetmeasurement object and the heat flux sensor heated to the designatedtemperature.
 17. The method of claim 16, wherein upper portions of thefirst heat source and the second heat source are insulated by aninsulator.
 18. The method of claim 16, wherein a region above the heatflux sensor is heated up to the designated temperature to preventgeneration of heat flux above the heat flux sensor.
 19. The method ofclaim 16, wherein the designated temperature is in a range of 70 to 90°C.
 20. The method of claim 16, wherein the thermal insulationperformance of the target measurement object is measured by the firstheat flux measured from the heat flux sensor after the heat flux sensoris in contact with the target measurement object and a designated timehas elapsed.
 21. The method of claim 16, wherein the measuring of thethermal insulation performance of the target measurement objectincludes: measuring first thermal conductivities of plural samples usinga thermal conductivity measurement apparatus; measuring the second heatfluxes of the samples using the heat flux sensor and acquiring firstdata regarding relations between the first thermal conductivities andthe second heat fluxes; and estimating thermal conductivity of thetarget measurement object using the second heat flux based on the firstdata and measuring the thermal insulation performance of the targetmeasurement object.
 22. The method of claim 16, wherein the measuring ofthe thermal insulation performance of the target measurement objectincludes: measuring first thermal conductivities using a thermalconductivity measurement apparatus while adjusting an inner pressure ofa vacuum insulator of which the inner pressure is adjustable; measuringsecond heat fluxes of the vacuum insulator using the heat flux sensorand acquiring first data regarding relations between the first thermalconductivities and the second heat fluxes; and estimating thermalconductivity of the target measurement object using the second heat fluxbased on the first data and measuring the thermal insulation performanceof the target measurement object.
 23. The method of claim 22, furthercomprising: measuring third heat fluxes of the vacuum insulator atrespective degrees of the inner pressure of the vacuum insulator usingthe heat flux sensor while adjusting the inner pressure of the vacuuminsulator of which the inner pressure is adjustable to the respectivedegrees; and correcting the first data by comparing the third heatfluxes with third data regarding relations between the degree of thevacuum of the inside and the thermal conductivity of the vacuuminsulator.